Off topic:how to calculate all atom to all atom distances for less than 5 angstrom

Question

[python]

how to calculate all atom to all atom distances for less than 5 angstrom i have extract coordinate from following code now what i have to do for calculating all atom to all atom distances for less than 5 angstrom

for model in structure:
    for chain in model:
        for residue in chain:
            for atom in residue:
                print (atom.get_vector(),atom.name)