input: Write a function to calculate the square root of a user-defined positive number. If the input number is less than or equal to zero, return -1.
  assert calculate_square_root(100)==10.0
  assert calculate_square_root(16)==4.0
  assert calculate_square_root(9)==3.0
  assert calculate_square_root(25)==5.0
  assert calculate_square_root(-1)==-1
  assert calculate_square_root(0)==-1
output: def calculate_square_root(num):
      if num <= 0:
          return -1
      return num ** 0.5