treatment of cells with constant formula

[Connum]

I don't know if "constant formula" is an official term, but I read it somewhere. What I mean is the following:
It's possible to prefix a quoted cell content with an equal sign, e.g. in order to prevent Excel from losing any leading zeros when the content is numeric, for example:
...;="0001234";...
When I use this library to parse files containing this notation, the value is simply read as the whole string including the equal sign and quotes (="0001234 in the case of the example).

So I have to iterate over all fields and replace this if it occurs.
I don't think this is part of the CSV spec, but rather something that Excel and other tools support, but would it be possible to add this as a parsing option?