macro only for tikz

I have a macro written as newcommand which contains a complete new tikz-environment.

How could one make a macro out of this that only contains the content of the tikz-environment, so that if one wants to have this drawing multiple times, it is drawn in one single tikz-environment?

I know I could simply strip the declaration of the tikz-environment in my macro, but that would let me use the macro outside a tikz-environment too.

Examples:

I have a macro similar to the following one:

newcommand{myTikzMacro}{
  begin{tikzpicture}
    draw (0,0) rectangle (1,1);
    draw (1,1) rectangle (2,0);
  end{tikzpicture}

Now I could use the macro multiple times after each other like this:

myTikzMacro 
myTikzMacro 

But then multiple tikz-environments would be used. To avoid that I’d be able to make this macro:

newcommand{myTikzMacro2}{
    draw (0,0) rectangle (1,1);
    draw (1,1) rectangle (2,0);

And use it as followed:

begin{tikzpicture}
  myTikzMacro2
  myTikzMacro2
end{tikzpicture}

But this would enable me to use the macro outside a tikzpicture environment too which I’d like to avoid too.

Is there a way to declare macros only available/visible within tikzpicture environments? (maybe with pgfkeys)

tikzifinpicture{true branch}{false branch}

newcommand*{myTikzPicture}
{tikzifinpicture
    {%
     draw (0,0) rectangle (1,1);
     draw (1,1) rectangle (2,0);
    }%
    {%
     GenericError{}{Unallowed command}
             {stringmyTikzPicturespace can be used only inside a tikz picture.}{}%
    }%
}