'Replaces ``search_for`` in the given ``string`` with ``replace_with``.
``search_for`` is used as a literal string. See `Replace String
Using Regexp` if more powerful pattern matching is needed.
If you need to just remove a string see `Remove String`.
If the optional argument ``count`` is given, only that many
occurrences from left are replaced. Negative ``count`` means
that all occurrences are replaced (default behaviour) and zero
means that nothing is done.
A modified version of the string is returned and the original
string is not altered.
Examples:
| ${str} =        | Replace String | Hello, world!  | world | tellus   |
| Should Be Equal | ${str}         | Hello, tellus! |       |          |
| ${str} =        | Replace String | Hello, world!  | l     | ${EMPTY} | count=1 |
| Should Be Equal | ${str}         | Helo, world!   |       |          |'

def replace_string(self, string, search_for, replace_with, count=(-1)):

    count = self._convert_to_integer(count, 'count')
    return string.replace(search_for, replace_with, count)
