GMYC.py    Implements the single threshold general mixed Yule coalescent 
           (GMYC) model which was first proposed by Pons et al 
           (Sequence-Based Species Delimitation for the DNA Taxonomy 
           of Undescribed Insects. Systematic Biology, 55(4), 595–609)
           This model requires the input tree to be time calibrated 
           ultrametric tree, in other words, the branch length of the 
           input ultrametric tree should represent time. 
           The most commonly used programs for getting an ultrametric
           tree are BEAST, DPPDIV and r8s. There is also an R 
           implementation of this model called "splits" by Tomochika 
           Fujisawa (http://barralab.bio.ic.ac.uk/downloads.html)
           To find out how to use it, type ./GMYC.py