func (c *Context) Get(key string) string {
	c.lock.RLock()
	defer c.lock.RUnlock()
	if v, ok := c.contextMap[key]; ok {
		return v.(string)
	}
	return ""
}
Get retrieves a string value from Context.
Get returns an empty string if key not found
package colly
import (
	"sync"
)
type Context struct {
	contextMap map[string]interface{}
	lock       *sync.RWMutex
}
func NewContext() *Context {
	return &Context{
		contextMap: make(map[string]interface{}),
		lock:       &sync.RWMutex{},
	}
}
func (c *Context) UnmarshalBinary(_ []byte) error {
	return nil
}
func (c *Context) MarshalBinary() (_ []byte, _ error) {
	return nil, nil
}
func (c *Context) Put(key string, value interface{}) {
	c.lock.Lock()
	c.contextMap[key] = value
	c.lock.Unlock()
}