(n, r)
This function calculates nCr.
This function calculates nCr.
This function calculates nCr .
def combination(n, r):
    """This function calculates nCr."""
    if n == r or r == 0:
        return 1
    else:
        return combination(n-1, r-1) + combination(n-1, r)
def combination ( n , r ) : if n == r or r == 0 : return 1 else : return combination ( n - 1 , r - 1 ) + combination ( n - 1 , r )