'Flips and flattens the module_attributes dictionary from:
module => [Attribute, ...]
To:
Attribute => module
This is useful so that we can find the module to use, given an
attribute.'

@staticmethod
def _build_attribute_modules(module_attributes):

    attribute_modules = {}
    for (module, attributes) in list(module_attributes.items()):
        for attribute in attributes:
            attribute_modules[attribute] = module
    return attribute_modules
