The editor for a regular expression is essentially just a single text field. Operators in a regular expression are the Kleene star (*), the ``or'' operator (+), parentheses are also usable, and concatenation is accomplished by making symbols adjacent.
To make expressions
for this program to work with,
type them in the field.
Adjacent symbols
imply concatenation.
No symbol is used.
Many or nothing,
Asterisk (*) is the Kleine star.
What precedes repeats.
Additionally,
if you want an "or" symbol
the plus (+) should be used.
Screaming nothingness,
exclamations (!) are special.
They act as lambda.
Formatting errors
will be reported to you
when you choose actions.