input: Write a function to port a Java code snippet to Python 3, which converts a public class with a method that adds two integers into a Python function. If the input is a Java class with a method taking two integers and returning their sum, the output should be a Python function that does the same.
  
  assert foo(3, 4)==7
  assert foo(0, 0)==0
  assert foo(-1, 1)==0
  assert foo(-5, -3)==-8
  assert foo(10, 20)==30
output: def foo(a, b):
      return a + b