Understand how ARG and FROM interact
FROMinstructions support variables that are declared by anyARGinstructions that occur before the firstFROM.
AnARGdeclared before aFROMis outside of a build stage, so it
can't be used in any instruction after aFROM. To use the default value of
anARGdeclared before the firstFROMuse anARGinstruction without
a value inside of a build stage: