Turns on text attributes in terminal, including bold text, italics, underline, etc. Note that not all terminals support each attribute.
Usage
attr_on(...)
Arguments
...
characters indicating attributes to turn on. "bf" for bold face; "ft" for faint; "it" for italics; "ul" for underline; "sb" for slow blink; "fb" for fast blink; "rv" for reverse video (invert bg and fg colors); "st" for strike-through