returns True if you are running inside a python virtual environment.
    (DOES NOT WORK IF IN IPYTHON AND USING A VIRTUALENV)

    sys.prefix gives the location of the virtualenv

    Notes:
        It seems IPython does not respect virtual environments properly.
        TODO: find a solution
        http://stackoverflow.com/questions/7335992/ipython-and-virtualenv-ignoring-site-packages

    References:
        http://stackoverflow.com/questions/1871549/python-determine-if-running-inside-virtualenv

    CommandLine:
        python -m utool.util_sysreq in_virtual_env

    Example:
        >>> # DISABLE_DOCTEST
        >>> from utool.util_sysreq import *  # NOQA
        >>> import utool as ut
        >>> result = in_virtual_env()
        >>> print(result)

def in_virtual_env():
    """
    returns True if you are running inside a python virtual environment.
    (DOES NOT WORK IF IN IPYTHON AND USING A VIRTUALENV)

    sys.prefix gives the location of the virtualenv

    Notes:
        It seems IPython does not respect virtual environments properly.
        TODO: find a solution
        http://stackoverflow.com/questions/7335992/ipython-and-virtualenv-ignoring-site-packages

    References:
        http://stackoverflow.com/questions/1871549/python-determine-if-running-inside-virtualenv

    CommandLine:
        python -m utool.util_sysreq in_virtual_env

    Example:
        >>> # DISABLE_DOCTEST
        >>> from utool.util_sysreq import *  # NOQA
        >>> import utool as ut
        >>> result = in_virtual_env()
        >>> print(result)
    """
    import sys
    has_venv = False
    if hasattr(sys, 'real_prefix'):
        # For virtualenv module
        has_venv = True
    elif hasattr(sys, 'base_prefix'):
        # For venv module
        has_venv = sys.base_prefix != sys.prefix
    return has_venv