'Ensures that vars contained in the parameter passed in are
returned as a list of dictionaries, to ensure for instance
that vars loaded from a file conform to an expected state.'

def _preprocess_vars(self, a):

    if (a is None):
        return None
    elif (not isinstance(a, list)):
        data = [a]
    else:
        data = a
    for item in data:
        if (not isinstance(item, MutableMapping)):
            raise AnsibleError(('variable    files    must    contain    either    a    dictionary    of    variables,    or    a    list    of    dictionaries.    Got:    %s    (%s)' % (a, type(a))))
    return data
