Fix PHP < 7.1 error.

composer.json

@@ -16,6 +16,7 @@
 		"issues": "https://github.com/pressbooks/pressbooks-aldine/issues",
 		"forum": "https://discourse.pressbooks.org/"
 	},
+	"sort-package": true,
 	"require": {
 		"php": ">=7",
 		"composer/installers": "~1.0",
@@ -26,6 +27,7 @@
 	"require-dev": {
 		"humanmade/coding-standards": "^0.2.1",
 		"squizlabs/php_codesniffer": "^2.8.0",
+		"symfony/console": "^3.4",
 		"wpreadme2markdown/wp2md": "^3.0"
 	},
 	"scripts": {

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "98d5bc8ff0e066bda4383130af3ae190",
+    "content-hash": "723debc6d424bd1cd8c84d1d42f014c6",
     "packages": [
         {
             "name": "composer/installers",
@@ -366,6 +366,53 @@
             "description": "Human Made coding standards",
             "time": "2017-08-31T03:33:08+00:00"
         },
+        {
+            "name": "psr/log",
+            "version": "1.0.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/php-fig/log.git",
+                "reference": "4ebe3a8bf773a19edfe0a84b6585ba3d401b724d"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/php-fig/log/zipball/4ebe3a8bf773a19edfe0a84b6585ba3d401b724d",
+                "reference": "4ebe3a8bf773a19edfe0a84b6585ba3d401b724d",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Psr\\Log\\": "Psr/Log/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "PHP-FIG",
+                    "homepage": "http://www.php-fig.org/"
+                }
+            ],
+            "description": "Common interface for logging libraries",
+            "homepage": "https://github.com/php-fig/log",
+            "keywords": [
+                "log",
+                "psr",
+                "psr-3"
+            ],
+            "time": "2016-10-10T12:19:37+00:00"
+        },
         {
             "name": "squizlabs/php_codesniffer",
             "version": "2.9.1",
@@ -446,20 +493,21 @@
         },
         {
             "name": "symfony/console",
-            "version": "v4.0.1",
+            "version": "v3.4.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/console.git",
-                "reference": "2ff6acc1342a0e7c3ad757a80fd837f5b22535a1"
+                "reference": "2cdef78de8f54f68ff16a857e710e7302b47d4c7"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/2ff6acc1342a0e7c3ad757a80fd837f5b22535a1",
-                "reference": "2ff6acc1342a0e7c3ad757a80fd837f5b22535a1",
+                "url": "https://api.github.com/repos/symfony/console/zipball/2cdef78de8f54f68ff16a857e710e7302b47d4c7",
+                "reference": "2cdef78de8f54f68ff16a857e710e7302b47d4c7",
                 "shasum": ""
             },
             "require": {
-                "php": "^7.1.3",
+                "php": "^5.5.9|>=7.0.8",
+                "symfony/debug": "~2.8|~3.0|~4.0",
                 "symfony/polyfill-mbstring": "~1.0"
             },
             "conflict": {
@@ -468,11 +516,11 @@
             },
             "require-dev": {
                 "psr/log": "~1.0",
-                "symfony/config": "~3.4|~4.0",
+                "symfony/config": "~3.3|~4.0",
                 "symfony/dependency-injection": "~3.4|~4.0",
-                "symfony/event-dispatcher": "~3.4|~4.0",
+                "symfony/event-dispatcher": "~2.8|~3.0|~4.0",
                 "symfony/lock": "~3.4|~4.0",
-                "symfony/process": "~3.4|~4.0"
+                "symfony/process": "~3.3|~4.0"
             },
             "suggest": {
                 "psr/log": "For using the console logger",
@@ -483,7 +531,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "4.0-dev"
+                    "dev-master": "3.4-dev"
                 }
             },
             "autoload": {
@@ -510,7 +558,63 @@
             ],
             "description": "Symfony Console Component",
             "homepage": "https://symfony.com",
-            "time": "2017-12-04T12:31:58+00:00"
+            "time": "2017-12-02T18:20:11+00:00"
+        },
+        {
+            "name": "symfony/debug",
+            "version": "v4.0.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/debug.git",
+                "reference": "26a15dab86c3820473716be4f846eac774ad4ad9"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/debug/zipball/26a15dab86c3820473716be4f846eac774ad4ad9",
+                "reference": "26a15dab86c3820473716be4f846eac774ad4ad9",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.1.3",
+                "psr/log": "~1.0"
+            },
+            "conflict": {
+                "symfony/http-kernel": "<3.4"
+            },
+            "require-dev": {
+                "symfony/http-kernel": "~3.4|~4.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.0-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Component\\Debug\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony Debug Component",
+            "homepage": "https://symfony.com",
+            "time": "2017-11-21T09:27:49+00:00"
         },
         {
             "name": "symfony/polyfill-mbstring",