Chemfig: put + between two formulas

Question

I want to draw a simple structural chemical formula with the chemfig package in Latex.

It schould look like the output of the code below, but i don't think that this is the right way to write it because the whole figure should be one formula with a plus in the middle and not two.

\setatomsep{1cm}
\chemfig{CH_4} + \chemfig{C([3]-H)([5]-H)=C([1]-H)([7]-H)}

Answer 1

\schemestart
  \chemfig{...}
   \+
  \chemfig{...}
\schemestop

is the way described in the manual:

The use of a “\+” macro that displays a + sign is available between the commands \schemestart and \schemestop.