def get_enum(s, enum_class):
    """Get an enum from a string where the enum class is assumed to have 
    all upper-case keys, returning None if the key is not found.
    
    Args:
        s (str): Key of enum to find, case-insensitive.
        enum_class (:class:`Enum`): Enum class to search.

    Returns:
        The enum if found, otherwise None.

    """
    enum = None
    if s:
        s_upper = s.upper()
        try:
            enum = enum_class[s_upper]
        except KeyError:
            pass
    return enum