Constant UPDATE_FIELDS 

pub const UPDATE_FIELDS: &str = r#"mutation($input:UpdateProjectV2ItemFieldValueInput!,$second:UpdateProjectV2ItemFieldValueInput!,$third:UpdateProjectV2ItemFieldValueInput!,$clear:ClearProjectV2ItemFieldValueInput!,$writeSecond:Boolean!,$writeThird:Boolean!,$writeClear:Boolean!){updateProjectV2ItemFieldValue(input:$input){projectV2Item{id}} second:updateProjectV2ItemFieldValue(input:$second) @include(if:$writeSecond){projectV2Item{id}} third:updateProjectV2ItemFieldValue(input:$third) @include(if:$writeThird){projectV2Item{id}} cleared:clearProjectV2ItemFieldValue(input:$clear) @include(if:$writeClear){projectV2Item{id}}}"#;

Writes up to three board fields and an optional clear in one ordered mutation.