code: function verifyOptionType(sourcePath, name, value) {
    if (typeof value === 'object') {
      var msg = 'POSTCSS-HASH-CLASSNAME ERROR: Object value not supported for option "' + name + '"!';
      console.error(msg);
      throw new Error(msg);
    } else if (!sourcePath && typeof value === 'function') {
      var msg = 'POSTCSS-HASH-CLASSNAME ERROR: Source file\'s path isn not determined - only explicit values for option "' + name + '" supported! Value passed is a function.';
      console.error(msg);
      throw new Error(msg);
    } else if (!sourcePath && ((value.toString().indexOf('[') >= 0) || (value.toString().indexOf(']') >= 0))) {
      var msg = 'POSTCSS-HASH-CLASSNAME WARNING: Source file\'s path isn not determined - only explicit values for option "' + name + '" supported! Value passed detected as using templating.';
      console.warn(msg);
    }
  }
docs: Makes sure option is a string and outputs a warning to console if it seems like option is using templating
  @param sourcePath Source file's path
  @param name Validating option's name
  @param value Validating option's value