@param value [Symbol]One of three Symbols: :major,
:minor or :patch.
# File lib/bundler/gem_version_promoter.rb, line 48
def level=(value)
v = case value
when String, Symbol
value.to_sym
end
raise ArgumentError, "Unexpected level #{v}. Must be :major, :minor or :patch" unless [:major, :minor, :patch].include?(v)
@level = v
end
