code: def hse_output(pdb_file, file_type):
      
      # Get the first model
      my_structure = StructureIO(pdb_file)
      model = my_structure.first_model
  
      # Calculate HSEalpha
      exp_ca = HSExposureCA(model)
      # Calculate HSEbeta
      exp_cb = HSExposureCB(model)
      # Calculate classical coordination number
      exp_fs = ExposureCN(model)
  
      return
docs: The solvent exposure of an amino acid residue is important for analyzing,
      understanding and predicting aspects of protein structure and function [73].
      A residue's solvent exposure can be classified as four categories: exposed, partly exposed,
      buried and deeply buried residues. Hamelryck  et al. [73] established a new 2D measure that provides a
      different view of solvent exposure, i.e. half-sphere exposure (HSE). By conceptually dividing the sphere
      of a residue into two halves- HSE-up and HSE-down, HSE provides a more detailed description of an amino
      acid residue's spatial neighborhood. HSE is calculated by the hsexpo module implemented in the BioPython
      package [74] from a PDB file.
  
      http://onlinelibrary.wiley.com/doi/10.1002/prot.20379/abstract
  
      Args:
          pdb_file:
  
      Returns: