input: Write a function to explain the difference between a list and a tuple in Python. The function should return a string explaining that a list is mutable and can be changed, while a tuple is immutable and cannot be changed. A list has square brackets around it, and a tuple has parentheses around it. Lists are used when the data needs to be changed, while tuples are used when the data is fixed and cannot be changed.
  
  assert explain_list_tuple()== "The difference between a list and a tuple in Python is that a list is mutable, meaning its contents can be changed, while a tuple is immutable, meaning its contents cannot be changed. A list has square brackets around it, while a tuple has parentheses around it. Lists are used when the data needs to be changed, while tuples are used when the data is fixed and cannot be changed."
output: def explain_list_tuple():
      return "The difference between a list and a tuple in Python is that a list is mutable, meaning its contents can be changed, while a tuple is immutable, meaning its contents cannot be changed. A list has square brackets around it, while a tuple has parentheses around it. Lists are used when the data needs to be changed, while tuples are used when the data is fixed and cannot be changed."