Revert "Reducing conflicts with other libraries like illuminate/support by wrapping the tap method in a function_exists conditional."

This reverts commit 8d74945391.

cli/includes/helpers.php

@@ -108,7 +108,6 @@ function should_be_sudo()
     }
 }
 
-if (! function_exists('tap')) {
 /**
  * Tap the given value.
  *
@@ -122,7 +121,6 @@ function tap($value, callable $callback)
 
     return $value;
 }
-}
 
 /**
  * Get the user