src/Expression.php
protected function _param($value)
    {
        // supports array
        if (is_array($value)) {
            return array_map(__METHOD__, $value);
        }

        $name = ':'.$this->_paramBase;
        $this->_paramBase++;
        $this->params[$name] = $value;

        return $name;
    }
protected function _param($value)
    {
        // supports array
        if (is_array($value)) {
            return array_map(__METHOD__, $value);
        }

        $name = ':'.$this->_paramBase;
        $this->_paramBase++;
        $this->params[$name] = $value;

        return $name;
    }
Converts value into parameter and returns reference. Use only during
query rendering. Consider using `_consume()` instead, which will
also handle nested expressions properly.

@param string|array $value String literal or array of strings containing input data

@return string|array Name of parameter or array of names