Write a function in Python to calculate the sum of all the values in a list of dictionaries using list comprehension.
[
  {'key1': 3, 'key2': 4},
  {'key3': 10, 'key4': 16},
  {'key5': 3, 'key6': 9}
]
def sum_values(list_of_dicts): 
  return sum([v for d in list_of_dicts for v in d.values()])