Pythonコードでpythonを見つけます.exeのパス

#coding:utf-8
import os
def getPythonPath():
    if os.getenv("PYTHON")!=None:
        return os.getenv("PYTHON")
    sys_path=os.getenv("path")
    li=sys_path.split(';')
    li.sort()
    for i in range(len(li)):
        if li[i].find('Python')!=-1 or li[i].find('python')!=-1:
            python_path.append(li[i])
    for i in range(len(python_path)):
        try:
            os.chdir(python_path[i])
            python_exe=os.listdir(python_path[i])
            for j in range(len(python_exe)):
                if python_exe[j].find('python.exe')==0:
                    return python_path[i]+os.sep+python_exe[j] 
        except:
            pass
        
print getPythonPath()