Adding an OR condition in Findall, Lxml

I have the following findall expression :

for r in p.findall('.//r'):
                 for a in r.findall('.//br'):
                    text+= " "
                 for c in r.findall('.//tab'):
                     text+= " "  

And i want to add a space in the text variable if i come across the tag "br" or "tab" , but I want to use a single expression rather than 2 separate ones. something like:

for a in r.findall('.//br'|'.//tab'):

but this returns an unsupported operand type error.

TypeError: unsupported operand type(s) for |: 'str' and 'str'

What is the right syntax for this?