code: def set_format(variant_call, field_name, value, vcf_object=None):
      """Sets a field of the info map of the `VariantCall` to the given value(s).
  
      `variant_call.info` is analogous to the FORMAT field of a VCF call.
  
      Example usage:
      with vcf.VcfReader('/path/to/my.vcf') as vcf_reader:
        for variant in vcf_reader:
          first_call = variant.calls[0]
          # Type can be inferred for reserved VCF fields.
          set_format(first_call, 'AD', 25)
          # Specify the reader explicitly for unknown fields.
          set_format(first_call, 'MYFIELD', 30, vcf_reader)
  
      Args:
        variant_call: VariantCall proto. The VariantCall to modify.
        field_name: str. The name of the field to set.
        value: A single value or list of values to update the VariantCall with.
          The type of the value is determined by the `vcf_object` if one is given,
          otherwise is looked up based on the reserved FORMAT fields in the VCF
          specification.
        vcf_object: (Optional) A VcfReader or VcfWriter object. If not None, the
          type of the field is inferred from the associated VcfReader or VcfWriter
          based on its name. Otherwise, the type is inferred if it is a reserved
          field.
      """
      if field_name == _GL:
          set_gl(variant_call, value)
          return
      if field_name == _GT:
          set_gt(variant_call, value)
          return
  
      if vcf_object is None:
          set_field_fn = vcf_constants.reserved_format_field_set_fn(
              field_name
          )
      else:
          set_field_fn = (
              vcf_object.field_access_cache.format_field_set_fn(
                  field_name
              )
          )
      set_field_fn(variant_call.info, field_name, value)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from third_party.nucleus.protos import struct_pb2
  from third_party.nucleus.protos import variants_pb2
  from third_party.nucleus.util import struct_utils
  from third_party.nucleus.util import vcf_constants
label_desc: Use image node_id 1 for calling a global function with example usage: set_format(variant_call, field_name, value, vcf_object) without return types