Replace the first occurrence of
from in this string.
Returns a new string, which is this string
except that the first match of
from, starting from
is replaced by the result of calling
replace with the match object.
startIndex is by default set to 0. If provided, it must be
an integer in the range
[0 .. len], where
len is this string's length.
String replaceFirstMapped(Pattern from, String replace(Match match), [int startIndex = 0]);