code: public static SourceLineAnnotation fromVisitedInstruction(BytecodeScanningDetector visitor, int pc) {
          return fromVisitedInstructionRange(visitor.getClassContext(), visitor, pc, pc);
      }
docs: Factory method for creating a source line annotation describing the
  source line number for the instruction being visited by given visitor.
  
  @param visitor
  a BetterVisitor which is visiting the method
  @param pc
  the bytecode offset of the instruction in the method
  @return the SourceLineAnnotation, or null if we do not have line number
  information for the instruction