input: Write a Python function to create a BankAccount class with methods to deposit, withdraw, and show the balance.
  assert account.show_balance() == 'Your balance is 100.0'
  assert account.deposit(50.0) == 150.0
  assert account.withdraw(75.0) == 75.0
  assert account.withdraw(200.0) == 'Insufficient funds'
output: class BankAccount:
      def __init__(self, balance=0.0):
          self.balance = balance
  
      def deposit(self, amount):
          self.balance += amount
          return self.balance
  
      def withdraw(self, amount):
          if amount > self.balance:
              return 'Insufficient funds'
          else:
              self.balance -= amount
              return self.balance
  
      def show_balance(self):
          return f'Your balance is {self.balance}'
  
  # Example usage:
  account = BankAccount(100.0)