#### 4.5.4 ReplaceOnce

Syntax: `ReplaceOnce [`string`]`
Abbreviation: `R1`

acts just like `Replace`, but without any interaction with you (unless there is no find string). The first string matched by the last search pattern, if it exists, is replaced by the given replacement string.

If the optional argument string is not specified, you can enter it on the input line, the default being the last string used.