input: Write a python function to calculate the time complexity of a given code snippet.
  assert calculate_time_complexity("for i in range(n): for j in range(n): pass") == "O(n²)"
  assert calculate_time_complexity("for i in range(n): pass") == "O(n)"
  assert calculate_time_complexity("for i in range(n): for j in range(n): for k in range(n): pass") == "O(n³)"
output: def calculate_time_complexity(code_snippet: str) -> str:
      lines = code_snippet.split('\n')
      max_depth = 0
      current_depth = 0
  
      for line in lines:
          stripped_line = line.strip()
          if stripped_line.startswith('for '):
              current_depth += 1
              if current_depth > max_depth:
                  max_depth = current_depth
          elif stripped_line == 'pass':
              current_depth = 0
  
      return f"O(n^{max_depth})" if max_depth > 1 else f"O(n)" if max_depth == 1 else "O(1)"