def quote(value)
      string   = value.to_s
      unquoted = unquote(string)
      escaped  = unquoted.gsub(QuoteNotEscapedMatcher, "\\\"")
      %Q{"#{escaped}"}
    end
def quote(value)
      string   = value.to_s
      unquoted = unquote(string)
      escaped  = unquoted.gsub(QuoteNotEscapedMatcher, "\\\"")
      %Q{"#{escaped}"}
    end
Returns +value+ surrounded by double quotes. This method is idempotent
 so +value+ will only be quoted once regardless of how may times the
 method is called on it.

 @example Quoting a BEL parameter.
    quote("apoptotic process")
    # => "\"apoptotic process\""
 @example Escaping quotes within a value.
    quote("vesicle fusion with \"Golgi apparatus\"")
    # => "\"vesicle fusion with \\\"Golgi apparatus\\\"\""

 @parameter [#to_s] value a value to be quoted
 @return    [String] value surrounded by double quotes