def hse_output(pdb_file, file_type):
    """
    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:

    """
    # 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