let default_genome_providers = [   Reference_genome.Specification.Default.Name.b37, pull_b37;   Reference_genome.Specification.Default.Name.b37decoy, pull_b37decoy;   Reference_genome.Specification.Default.Name.b38, pull_b38;   Reference_genome.Specification.Default.Name.hg38, pull_hg38;   Reference_genome.Specification.Default.Name.hg18, pull_hg18;   Reference_genome.Specification.Default.Name.hg19, pull_hg19;   Reference_genome.Specification.Default.Name.mm10, pull_mm10; ]