When we normalize call, we need to add correct import for method
            to function transformation.

            a.max()

            for numpy array will become:

            numpy.max(a)

            so we have to import numpy.

def visit_Module(self, node):
        """
            When we normalize call, we need to add correct import for method
            to function transformation.

            a.max()

            for numpy array will become:

            numpy.max(a)

            so we have to import numpy.
        """
        self.skip_functions = True
        self.generic_visit(node)
        self.skip_functions = False
        self.generic_visit(node)
        new_imports = self.to_import - self.globals
        imports = [ast.Import(names=[ast.alias(name=mod[17:], asname=mod)])
                   for mod in new_imports]
        node.body = imports + node.body
        self.update |= bool(imports)
        return node