The `define` form supports a shorthand for defining functions.

This `if` expression can be refactored to an equivalent expression using `and`.

This `for-each` operation can be replaced with a `for` loop.

The `apply` function accepts single arguments in addition to a trailing list argument.

Use the `#:when` keyword instead of `when` to reduce loop body indentation.

This `map` operation can be replaced with a `for/list` loop.

Using `cond` instead of `if` here makes `begin` unnecessary

This method chain made of nested `send` expressions can be written more clearly as a `send+` expression.

This `if`-`else` chain can be converted to a `cond` expression.