grapheme_substr    28 ext/intl/grapheme/grapheme.h PHP_FUNCTION(grapheme_substr);
grapheme_substr   371 ext/intl/grapheme/grapheme_string.c PHP_FUNCTION(grapheme_substr)
grapheme_substr   737 ext/intl/php_intl.c 	PHP_FE( grapheme_substr, grapheme_substr_args )