Function sp_phragmen::build_support_map

pub fn build_support_map<Balance, AccountId, FS, C, R>(
    elected_stashes: &Vec<AccountId>, 
    assignments: &Vec<(AccountId, Vec<PhragmenAssignment<AccountId, R>>)>, 
    stake_of: FS
) -> SupportMap<AccountId> where
    AccountId: Default + Ord + Member,
    Balance: Default + Copy + AtLeast32Bit,
    C: Convert<Balance, u64> + Convert<u128, Balance>,
    FS: Fn(&'r AccountId) -> Balance,
    R: PerThing + Mul<ExtendedBalance, Output = ExtendedBalance>, 

Build the support map from the given phragmen result.