join
Concatenates a list of values into a single string with a separator.
Takes a separator string followed by a list of values (from a pushmark-delimited argument list on the stack). The separator is inserted between each adjacent pair of values. Array arguments are flattened. Returns the resulting string; an empty string when no list values are given.
Uses Cow<str> for the separator and parts to avoid allocation
when the underlying SVs are already string-typed.
Synopsis
$str = join(',', @array);
$str = join(' ', 'hello', 'world');
$str = join('', @chars); # no separator