input: Write a function to suggest a valid Python syntax to calculate the sum of two variables using lambda. The function should take the variable values as input and return the lambda function that performs the addition operation.
  assert calculate_sum_syntax(3, 4) == "lambda a, b : a + b"
  assert calculate_sum_syntax(5, 7) == "lambda a, b : a + b"
  assert calculate_sum_syntax(0, 0) == "lambda a, b : a + b"
  assert calculate_sum_syntax(1, 1) == "lambda a, b : a + b"
  assert calculate_sum_syntax(-1, 1) == "lambda a, b : a + b"
output: def calculate_sum_syntax(x, y):
      return "lambda a, b : a + b"