How to add a node on a path edge in pylatex Tikz

Question

I'm able to create a path with the edge with

p1=TikZCoordinate(0,0)
p2=TikZCoordinate(2,3)

mypath=TikZPathList()
mypath.append(p1)
mypath.append('--')
mypath.append(p2)

tikz_code=TikZDraw(mypath)

tikz_code.dumps_as_content()

fig=TikZ()
fig.append(tikz_code)

print(fig.dumps_as_content())

which produce

\begin{tikzpicture}%
\path[draw] (0.0,0.0) -- (2.0,3.0);%
\end{tikzpicture}

but I cannot add a node on the edge mypath.append('node[midway,above] {$a$}') is an invalid coordinate string (accepting only '--' etc.) Creating a TikzNode doesn't work either.

Any suggestion?

I would like to achieve

\begin{tikzpicture}%
\path[draw] (1.0,4.0) -- node[midway,above] {$a$} ++(4.0,-2.0);%
\end{tikzpicture}%

but I can't find a way to add the node[midway,above] {$a$} in my path.