Prints an extended help message.

def print_extended_help():
    """
	Prints an extended help message.
	"""
    # initiate TextWrapper class, which will handle all of the string formatting
    w = textwrap.TextWrapper()
    w.expand_tabs = False
    w.width=110
    w.initial_indent = '    '
    w.subsequent_indent = '      '

    print('')
    print(textwrap.fill("<split> Complete parameter list:", initial_indent=''))
    print('')

    cmd = "--input : (required) csv file to split into training and test sets"
    print(w.fill(cmd))
    cmd = "\t\tColumns should be as follows:"
    print(w.fill(cmd))
    print('')
    cmd="\t\t    id, status, receptor_1, receptor_2, ..., receptor_N"
    print(w.fill(cmd))
    cmd="\t\t  CH44,      1,       -9.7,       -9.3, ...,      -10.2"
    print(w.fill(cmd))
    cmd="\t\t  ZN44,      0,       -6.6,       -6.1, ...,       -6.8"
    print(w.fill(cmd))
    print('')
    cmd="\t\tid is a unique molecular identifier"
    print(w.fill(cmd))
    cmd="\t\tstatus takes a value of '1' if the molecule is active and '0' otherwise."
    print(w.fill(cmd))
    cmd="\t\treceptor_1 through receptor_N are docking scores."
    print(w.fill(cmd))
    print('')

    tfrac = "--training_fraction : (optional) The fraction of input active molecules\
	allocated to the training set, e.g. 0.40. Defaults to allocate half to the training\
	set."
    print(w.fill(tfrac))
    print('')

    d2a = "--decoy_to_active : (optional) The decoy to active ratio to establish in the \
	training and validation sets. Defaults to maintain the input file ratio."
    print(w.fill(d2a))
    print('')