Write a function to convert tuple to a string.
def tup_string(tup1):
  str =  ''.join(tup1)
  return str
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a function to convert tuple to a string.
def tup_string(tup1):
  str =  ''.join(tup1)
  return str[/INST]assert tup_string(('e', 'x', 'e', 'r', 'c', 'i', 's', 'e', 's'))==("exercises")
assert tup_string(('p','y','t','h','o','n'))==("python")
assert tup_string(('p','r','o','g','r','a','m'))==("program")</s>