# manual_conversion_impl

A conversion that implements only a lookup table established explcitly by the user.

# add

    some_mc add src_pattern tgt_pattern

Indicate that in future, apply of `some_mc` should return `tgt_pattern` if the input is `src_pattern`.

# remove

    some_mc remove src_pattern

Indicate that in future, apply of `some_mc` will not return the previously stored value when `src_pattern` is the input; this re-instates the fallback.