Empty input passed certain problems

[kamn]

Certain problems incorrectly pass with empty inputs, for example Problem 2. If I run the default empty input on Problem 2, I get a successful completion. This exists for several other problems in the lower-tiers but doesn't seem to be a problem in the higher tiers.

[scimetfoo]

The cause of this is that = used as a unary operator evaluates to true. Could potentially evaluate the solution before formatting/replacing the blanks so that the equation always has valid Clojure expressions.