<human>:  What is a good Python code to determine if a string contains unique characters.
<bot>: Here is a Python code to determine if a string contains unique characters

import re

def is_unique(s):
  """
  Returns True if the string contains unique characters, False otherwise.
  """
  if len(s) == 0:
    return True
  else:
    return len(set(s)) == len(s)

# Enter the string
string = "cat"

# Calling the function
print((is_unique(string)))

#Example Output
# True

#Remember to inspect code for bugs.