human
What is a the Python code you requested given the following:
I am working on the file "Devel/V05/Frame2D_Output.ipynb".
The first task is:
Supports
Can you write Python code for it?
assistant
#Here is the Python code you requested.

@extend
class Frame2D:
    
    def list_supports(self):
        ans = []
        for node in self.nodes.values():
            if node.constraints:
                cl = tuple(node.constraints)
                if len(cl) < 3:
                    cl = cl + ('',)*(3-len(cl))
                ans.append((node.id,)+cl)
        return ans

##test:
f.list_supports()

##test:
t = f.write_table('supports','test-1')
t.file_name

##test:
%cat test-1.d/supports.csv

##test:
x = 'supports'
if hasattr(f.rawdata,x):
    delattr(f.rawdata,x)
%rm test-1.d/supports.csv
t = f.write_table(x,'test-1')
t.file_name

##test:
%cat test-1.d/supports.csv