input: Write a python function to perform basic arithmetic operations (+, -, *, /) on two numbers and return the result.
  assert calculator(10, 5, '+') == 15
  assert calculator(10, 5, '-') == 5
  assert calculator(10, 5, '*') == 50
  assert calculator(10, 5, '/') == 2
  assert calculator(10, 0, '/') == "Invalid Operation: Division by zero"
  assert calculator(10, 5, '%') == "Invalid Operator"
output: def calculator(a, b, operator):
      if operator == '+':
          return a + b
      elif operator == '-':
          return a - b
      elif operator == '*':
          return a * b
      elif operator == '/':
          if b != 0:
              return a / b
          else:
              return "Invalid Operation: Division by zero"
      else:
          return "Invalid Operator"