Creates a nested dictionary with and without a specified depth level

nested_dict.py

# Unlimited depth nested dictionary
def nested_dict():
  return defaultdict(nested_dict)

# Specify max depth of nested dictionary
def nested_dict(instance_type, max_depth):
    def _nested_dict(depth):
        if depth < max_depth:
            return defaultdict(partial(_nested_dict, depth + 1))

        return defaultdict(instance_type)

    return _nested_dict(1)

# Example usage:
depth_level = 3
nested = nested_dict(int, depth_level)

nested['level1']['level2']['level3'] += 1 # Can use without instantiation

print nested['level1']['level2']['level3'] # returns 1