A (minimally-tested) interpreter for Brook. Some notes:
"Unambiguous" code is taken to include unclosed non-zero loops, which can be executed once without ambiguity
Unmatched parentheses are assumed to be invalid syntax that's ignored; one consequence is that zero-prefixed parentheses are considered ambiguous until the program has finished being written
Reading input when no character/number is available returns 0, in analogy with the behavior of an empty queue
The continuities' programs as displayed in this interface are reconstructed from parsed code, and so may be slightly different from the actual code that's written to the continuity