print('{one} {two}'.format(one='hello', two='world', three='again'))
print('{one} {two} {three}'.format(one='hello', two='world', three='again'))
# or
print('{one} {two}'.format(one='hello', two='world'))
Used when a PEP 3101 format string that uses named fields is used with an argument that is not required by the format string.