@pimms.value<EOL><INDENT>def _sphere_radius(mesh, sphere_radius):<DEDENT>
if sphere_radius is not None: return sphere_radius<EOL>if mesh is None: return <NUM_LIT><EOL>rs = np.sqrt(np.sum(mesh.coordinates**<NUM_LIT:2>, axis=<NUM_LIT:0>))<EOL>mu = np.mean(rs)<EOL>sd = np.std(rs)<EOL>if sd/mu > <NUM_LIT>: warnings.war('<STR_LIT>')<EOL>return mu<EOL>
proj._sphere_radius is identical to proj.sphere_radius unless proj.sphere_radius is None and
proj.mesh is not None, in which case proj._sphere_radius is deduced from the mesh. For this
reason, _sphere_radius is used internally.
If both sphere_radius and mesh are None, then the default sphere radius is 100.