Return the key of the first property in a property list.
MSymbol mplist_key (MPlist * plist)
Return the key of the first property in a property list. The mplist_key() function returns the key of the first property in property list plist. If the length of plist is zero, it returns Mnil.
Copyright (C) 2001 Information-technology Promotion Agency (IPA)
Copyright (C) 2001-2011 National Institute of Advanced Industrial Science and Technology (AIST)
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