An [Attr] for which no fansi escape sequence exists
Which bits of the [Str.State] integer these [Attrs] will set to 1 when it is applied
1
escapeOpt the actual ANSI escape sequence corresponding to this Attr
Which bits of the [Str.State] integer these [Attrs] will override when it is applied
Apply these [Attrs] to the given [fansi.Str], making it take effect across the entire length of that string.
Combine this [fansi.Attr] with one or more other [fansi.Attr]s so they can be passed around together
Apply the current [Attrs] to the [Str.State] integer, modifying it to represent the state after all changes have taken effect