Checks whether a block contains no statements, expressions, comments, or
inner attributes.
Checks whether a block contains at most one statement or expression, and no
comments or attributes.
Returns true if the last line of pat_str has leading whitespace and it is wider than the
shape’s indent.
Returns true if formatting next_line_rhs is better on a new line when compared to the
original’s line formatting.
Rewrite the else keyword with surrounding comments.
Rewrite the divergent block of a let-else statement.
Returns true if a function call or a method call represented by the given span ends with a
trailing comma. This function is used when rewriting macro, as adding or removing a trailing
comma from macro can potentially break the code.