Offer a colour scheme that more clearly demonstrates the level of nesting.

[jonathanknowles]

The current colour scheme nests expressions with colours according to the expression type.

• additions are represented with the colour red
• multiplications are represented with the colour blue
• subtractions are represented with the colour green
• divisions are represented with the colour yellow

Consider adding a colour scheme that depends purely on the level of nesting, so that it's easier to comprehend deeply-nested expressions, regardless of the binary operators in use.