parse_expected

# File lib/spec/matchers/be.rb, line 88
        def parse_expected(expected)
          ["be_an_","be_a_","be_"].each do |prefix|
            handling_predicate!
            if expected.starts_with?(prefix)
              set_prefix(prefix)
              expected = expected.to_s.sub(prefix,"")
              [true, false, nil].each do |val|
                return val if val.to_s == expected
              end
              return expected.to_sym
            end
          end
        end