def get_venv_name(dockenv_name):
    """
    Helper function to split the user-defined virtual env name
    out of the full name that includes the dockenv tag

    :param dockenv_name: The full name to pull the virtual env name
                         out of
    """
    # Format of tage name if dockenv-**NAME**:latest
    venv_start = len("dockenv-")
    if dockenv_name.endswith(":latest"):
        venv_end = len(":latest") * -1
        return dockenv_name[venv_start:venv_end]
    return dockenv_name[venv_start:]