Use ODict for maps

def construct_mapping(self, node, deep=False):
    """
    Use ODict for maps
    """

    mapping = ODict()

    for key_node, value_node in node.value:
        key = self.construct_object(key_node, deep=deep)
        value = self.construct_object(value_node, deep=deep)

        mapping[key] = value

    return mapping