none is a blank function that does not parse anything.

default is a blank function that ignores an arbitrary number of spacing characters. They include ' ', '\t', '\r' and '\n'.

from_charset cs is a blank function that ignores an arbitrary number of characters from the character set cs.

line_comments ?blanks=cs delim is a blank function that behaves the same as from_charset cs, but it also ignores single-line comments starting by delim. The exception Invalid_argument when delim is empty or when it starts with a character of cs.