def _fix_mimic_icd(icd):
    """ Add the decimal to the correct location for the ICD code
    
    From the mimic documentation (https://mimic.physionet.org/mimictables/diagnoses_icd/):
    
        > The code field for the ICD-9-CM Principal and Other Diagnosis Codes
        > is six characters in length, with the decimal point implied between
        > the third and fourth digit for all diagnosis codes other than the V
        > codes. The decimal is implied for V codes between the second and third
        > digit.

    """
    icd = str(icd)
    if len(icd) == 3:
        icd = icd
    else:
        icd = [icd[:3], '.', icd[3:]]
        icd = ''.join(icd)
    return icd
