You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: config.go
    path of file: ./repos/chainlink/integration-tests/testconfig/vrfv2
    
    the code of the file until where you have to start completion: package testconfig

import (
	"errors"

	"github.com/ethereum/go-ethereum/common"

	vrf_common_config "github.com/smartcontractkit/chainlink/integration-tests/testconfig/common/vrf"
)

type Config struct {
	General           *General                             `toml:"General"`
	ExistingEnvConfig *ExistingEnvConfig                   `toml:"ExistingEnv"`
	Performance       *vrf_common_config.PerformanceConfig `toml:"Performance"`
}

func (c *Config) Validate() error {
	if c.General != nil {
		if err := c.General.Validate(); err != nil {
			return err
		}
	}
	if c.Performance != nil {
		if err := c.Performance.Validate(); err != nil {
			return err
		}
	}
	if c.ExistingEnvConfig != nil && *c.General.UseExistingEnv {
		if err := c.ExistingEnvConfig.Validate(); err != nil {
			return err
		}
	}
	return nil
}

type ExistingEnvConfig struct {
	*vrf_common_config.ExistingEnvConfig
	SubID *uint64 `toml:"sub_id"`
}

func (c *ExistingEnvConfig) Validate() error {
	if c.ExistingEnvConfig != nil {
		if err := c.ExistingEnvConfig.Validate(); err != nil {
			return err
		}
	}
	if !*c.CreateFundSubsAndAddConsumers {
		if c.SubID == nil {
			return errors.New("sub_id must be set when using existing environment")
		}

		if *c.SubID == 0 {
			return errors.New("sub_id must be positive value")
		}

		if c.LinkAddress != nil && !common.IsHexAddress(*c.LinkAddress) {
			return errors.New("link_address must be a valid hex address")
		}
	}

	return c.Funding.Validate()
}

ty
    
func (c *General) Validate() error {
	if c.General != nil {
		if err := c.General.Validate(); err != nil {
			return err
		}
	}
	if c.FulfillmentFlatFeeLinkPPMTier1 == nil || *c.FulfillmentFlatFeeLinkPPMTier1 == 0 {
		return errors.New("fulfilment_flat_fee_link_ppm_tier_1 must be set to a positive value")
	}
	if c.FulfillmentFlatFeeLinkPPMTier2 == nil || *c.FulfillmentFlatFeeLinkPPMTier2 == 0 {
		return errors.New("fulfilment_flat_fee_link_ppm_tier_2 must be set to a positive value")
	}
	if c.FulfillmentFlatFeeLinkPPMTier3 == nil || *c.FulfillmentFlatFeeLinkPPMTier3 == 0 {
		return errors.New("fulfilment_flat_fee_link_ppm_tier_3 must be set to a positive value")
	}
	if c.FulfillmentFlatFeeLinkPPMTier4 == nil || *c.FulfillmentFlatFeeLinkPPMTier4 == 0 {
		return errors.New("fulfilment_flat_fee_link_ppm_tier_4 must be set to a positive value")
	}
	if c.FulfillmentFlatFeeLinkPPMTier5 == nil || *c.FulfillmentFlatFeeLinkPPMTier5 == 0 {
		return errors.New("fulfilment_flat_fee_link_ppm_tier_5 must be set to a positive value")
	}
	if c.ReqsForTier2 == nil || *c.ReqsForTier2 < 0 {
		return errors.New("reqs_for_tier_2 must be set to a non-negative value")
	}
	if c.ReqsForTier3 == nil || *c.ReqsForTier3 < 0 {
		return errors.New("reqs_for_tier_3 must be set to a non-negative value")
	}
	if c.ReqsForTier4 == nil || *c.ReqsForTier4 < 0 {
		return errors.New("reqs_for_tier_4 must be set to a non-negative value")
	}
	if c.ReqsForTier5 == nil || *c.ReqsForTier5 < 0 {
		return errors.New("reqs_for_tier_5 must be set to a non-negative value")
	}

	return nil
}