Format returns a string representation of the expression.

HasSideEffects reports whether evaluation of e has side effects.

Imports returns true if path is imported by pkg.

LineStart returns the position of the start of the specified line within file f, or NoPos if there is no line of that number.

ReadFile reads a file and adds it to the FileSet so that we can report errors against it using lineStart.

Unparen returns e with any enclosing parentheses stripped.