input: Write a python function to find the position of the first occurrence of a character in a string.
  assert find_position("hello world", "o") == 4
  assert find_position("hello world", "w") == 6
  assert find_position("hello world", "x") == -1
output: def find_position(string, char):
      try:
          return string.index(char)
      except ValueError:
          return -1