Same as get_invocation_command_nodefault, except that if no tool is found,
        returns either the user-provided-command, if present, or the 'tool' parameter.

def get_invocation_command(toolset, tool, user_provided_command = [],
                           additional_paths = [], path_last = False):
    """ Same as get_invocation_command_nodefault, except that if no tool is found,
        returns either the user-provided-command, if present, or the 'tool' parameter.
    """
    assert isinstance(toolset, basestring)
    assert isinstance(tool, basestring)
    assert is_iterable_typed(user_provided_command, basestring)
    assert is_iterable_typed(additional_paths, basestring) or additional_paths is None
    assert isinstance(path_last, (int, bool))

    result = get_invocation_command_nodefault(toolset, tool,
                                              user_provided_command,
                                              additional_paths,
                                              path_last)

    if not result:
        if user_provided_command:
            result = user_provided_command[0]
        else:
            result = tool

    assert(isinstance(result, str))

    return result