def scheme(self):
        attrs = [self.input.resolveAttribute(attref)
                 for attref in self.columnlist]
        return scheme.Scheme(attrs)
Deletes a field from the Solr Collection. Will raise ValueError if the field doesn't exist. 
dataset/ETHPy150Open uwescience/raco/raco/algebra.py/Project.scheme--crossover with--dataset/ETHPy150Open moonlitesolutions/SolrClient/SolrClient/schema.py/Schema.delete_field