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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def platform_default():
 """Return the platform string for our execution environment. The returned value should map to one of the SCons/Platform/*.py files. Since we're architecture independent, though, we don't care about the machine architecture. """

    osname = os.name
    if osname == 'java':
        osname = os._osType
    if osname == 'posix':
        if sys.platform == 'cygwin':
            return 'cygwin'
        elif sys.platform.find('irix') != -1:
            return 'irix'
        elif sys.platform.find('sunos') != -1:
            return 'sunos'
        elif sys.platform.find('hp-ux') != -1:
            return 'hpux'
        elif sys.platform.find('aix') != -1:
            return 'aix'
        elif sys.platform.find('darwin') != -1:
            return 'darwin'
        else:
            return 'posix'
    elif os.name == 'os2':
        return 'os2'
    else:
        return sys.platform