SPLTokenProgram.approve constructor
      
      SPLTokenProgram.approve({ 
    
- required SPLTokenApproveLayout layout,
- required SolAddress account,
- required SolAddress delegate,
- required SolAddress owner,
- SolAddress programId = SPLTokenProgramConst.tokenProgramId,
- List<SolAddress> multiSigners = const [],
Approves a delegate. A delegate is given the authority over tokens on behalf of the source account's owner.
Implementation
factory SPLTokenProgram.approve(
    {required SPLTokenApproveLayout layout,
    /// The source account.
    required SolAddress account,
    /// The delegate.
    required SolAddress delegate,
    /// The source account owner.
    required SolAddress owner,
    SolAddress programId = SPLTokenProgramConst.tokenProgramId,
    /// Multisignature owner
    List<SolAddress> multiSigners = const []}) {
  return SPLTokenProgram(
      layout: layout,
      keys: SPLTokenUtils.buildKeys(
          keys: [account.toWritable(), delegate.toReadOnly()],
          owner: owner,
          multiSigners: multiSigners),
      programId: programId);
}