Paradox/pod/Edge.php
public function getFromId()
    {
        if (isset($this->_from)) {
            return $this->_from->getPod()->getId();
        } elseif (isset($this->_data['_from'])) {
            return $this->_data['_from'];
        } else {
            return null;
        }
    }
public function getFromId()
    {
        if (isset($this->_from)) {
            return $this->_from->getPod()->getId();
        } elseif (isset($this->_data['_from'])) {
            return $this->_data['_from'];
        } else {
            return null;
        }
    }
Get the id of the to node by checking for it in the actual _from property or checking an internal property.
This is used because when documents are retrieved from the server, we will not have a model in the _from property.
This allows us to lazy load any vertices we need later.
@return null|string