def char_replace(fname, remove_char, replace_char=""):
    """Replace all of one character from a given string.

       inputs:
       fname: String of filename to replace characters from
       remove_char: Character to remove
    Keyword Arguments:

       - replace_char -- Character to replace with. Default = "" (blank)

    Examples:
    >>> char_replace("test_:.txt", ":", "1")
    'test_1.txt'

    >>> char_replace("test_adding_nothing.txt", "_")
    'testaddingnothing.txt'

    >>> char_replace("test_adding_space.txt", "_", " ")
    'testaddingnothing.txt'

    >>> char_replace("test removing space.txt", " ", "_" )
    'test_removing_space.txt'

    """
    name_parts = fname.split(remove_char)
    new_name = replace_char.join(name_parts)
    return new_name