@vuntz I am still not sure which method to invoke to delete the attributes from node.
as there is no .delete() would it be one of those? 
>> puts node.methods | grep attr
apply_expansion_attributes
override_attrs
override_attrs=
consume_external_attrs
default_attrs
default_attrs=
attribute
attribute=
normal_attrs
construct_attributes
normal_attrs=
automatic_attrs
automatic_attrs=
consume_attributes
attribute?
load_attributes
each_attribute
include_attribute
load_attribute_by_short_filename