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.

IsFunctionNamed reports whether f is a top-level function defined in the given package and has one of the given names.

IsNamedType reports whether t is the named type with the given package path and one of the given names.

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.