input: Write a python function to reduce the number of function calls by passing parameters that are used multiple times.
  assert reduce_function_calls(2, 3, 4)==14
  assert reduce_function_calls(1, 5, 6)==11
  assert reduce_function_calls(0, 0, 0)==0
output: def reduce_function_calls(a, b, c):
      sum_ab = a + b
      sum_abc = sum_ab + c
      return sum_ab + sum_abc