src/Container.php
public function setAlias($aliasId, $id)
    {
        $this->aliases[strtolower($aliasId)] = strtolower($id);

        return $this;
    }
public function setAlias($aliasId, $id)
    {
        $this->aliases[strtolower($aliasId)] = strtolower($id);

        return $this;
    }
Set alias service id

@param string $aliasId The alias service id
@param string $id      The original service id

@return Container