original_string: protected function _literalArgumentFunction($name, $expression, $types = [], $return = 'string')
      {
          if (!is_string($expression)) {
              $expression = [$expression];
          } else {
              $expression = [$expression => 'literal'];
          }
  
          return $this->_build($name, $expression, $types, $return);
      }
code: protected function _literalArgumentFunction($name, $expression, $types = [], $return = 'string')
      {
          if (!is_string($expression)) {
              $expression = [$expression];
          } else {
              $expression = [$expression => 'literal'];
          }
  
          return $this->_build($name, $expression, $types, $return);
      }
code_tokens: protected function _literalArgumentFunction ( $ name , $ expression , $ types = [ ] , $ return = 'string' ) { if ( ! is_string ( $ expression ) ) { $ expression = [ $ expression ] ; } else { $ expression = [ $ expression => 'literal' ] ; } return $ this -> _build ( $ name , $ expression , $ types , $ return ) ; }
docstring: Helper function to build a function expression that only takes one literal
  argument.
  
  @param string $name name of the function to build
  @param mixed $expression the function argument
  @param array $types list of types to bind to the arguments
  @param string $return The return type for the function
  @return \Cake\Database\Expression\FunctionExpression
docstring_tokens: Helper function to build a function expression that only takes one literal argument .