func (c *Credentials) Get() (Value, error) {
	return c.provider.Retrieve()
}
Get returns the credentials value, or error if the credentials Value failed
to be retrieved.
package credentials
var Default = NewChainCredentials(&EnvProvider{}, &SharedCredentialsProvider{})
type Provider interface {
	Retrieve() (Value, error)
}
type Value struct {
	AccessKeyID string
	SecretAccessKey string
	ProviderName string
}
type Credentials struct {
	provider Provider
}
func NewCredentials(provider Provider) *Credentials {
	if provider == nil {
		provider = &EnvProvider{}
	}
	return &Credentials{
		provider: provider,
	}
}